There are a number of different types of bulk shipping containers in use today. Some of these containers include:                Paper, paperboard or cardboard boxes on pallets made of wood or other materials;        Smaller boxes, generally of paper, with or without bags or liners inside; and        Hard bins, for example Ropak™ and Linpac™ brand containers.        
Although disposable containers make up a significant proportion of the market, a returnable solution offers both economic and ergonomic advantages. These these markets are showing signs they are ready to convert to returnables, and there is a trend driven by both economic and ergonomic factors.
Containers for bulk fluid or granulated materials require systems for dispensing the materials at the point of use. Presently, containers are emptied by corner or side tear-away cutting, manual dump (of smaller boxes) or are side dumped, which methods do not permit direct flow control of the material. Where flow control is required, the containers must be emptied into metering devices, requiring additional equipment and material handling steps. Furthermore, these methods permit the materials to be exposed to the environment during dumping and may result in dust or residue being generated from the movement of the bulk material.
Some bulk containers include a hopper mechanism or a built-in dispensing port/valve but such devices add to the complexity and cost of the container and can be inconvenient or space-consuming for knock-down or disassemblable returnable containers.
By providing the dispensing mechanism in association with the emptying apparatus, the containers can be made more cost and volume efficient.
Such bulk containers have been developed which comprise a sleeve, effectively forming the sidewalls of the container, which are sandwiched between a pair of pallets that form the top and bottom of the container. Such a container (as shown in FIG. 1) is described in Canadian Patent Application No. 2,358,261, published Apr. 4, 2003 and incorporated herein by reference. These containers can readily be broken down for storage or return as the top and bottom pallets are removable and preferably nestable and the sleeve is substantially flattenable or foldable. The sleeves may be made from multiply corrugated paper and/or plastic to suit the specific requirements of the material to be contained.
These containers have good compressive strength in the vertical direction as the containers themselves must be capable of being stacked. Generally, this strength not only comes from the sidewall structure but usually involves the manner by which the top and bottom pallets constrain the edges of the sidewalls. However, because of the foldable nature of the sidewalls, these containers can be difficult to empty since once the top is removed, lateral forces on the walls can cause them to fold readily out of shape, making emptying by tipping or inversion problematic.